Machine for and method of cross stretching nonwoven webs



I y 1960 c. HARMON ETAL 2,945,283

MACHINE FOR AND METHOD OF CROSS STRETCHING NONWOVEN WEBS Filed Oct. 30, 1956 4 Sheets-Sheet 1 FIGJ - lNVEINTORS CARLYLE HARMON FRA'NKLIN WEI-LS SHOEMAKEFZ ATTORNEYS July 1960 c. HARMON ET.AL 2,945,233

MACHINE FOR AND METHOD OF CROSS STRETCHING NONWOVEN WEBS IN VENTOR S CARLYLE HARMON FRANKLIN WELLS SHOEMAKER ATTORNEYS July 19, 1960 c. HARMON ET AL MACHINE FOR AND METHOD OF CROSS STRETCHING NONWOVEN WEBS Filed Oct. 30, 1956 4 Sheets-Sheet 4 FIGJO EMAKER /7 4/5 .35 INVENTORS CARLYLE HARMO FRANKLIN vvELLs SHO BYM ATTORNEYS systems, particularly at normal economical production speeds for fabrics of this type.

Method of this invention In accordance with the present invention an unbonded web having a substantially uniform density throughout the area thereof formed of loosely associated textile fibers, such as a carded web made from a multiplicity of superposed conventional card webs, which carded web Weighs from approximately 100 to 5000 grains per square yard, in which the fibers are predominantly parallelized or oriented in the long direction, is subjected to a combined cross stretching and longitudinal shrinking operation to move the originally parallelized fibers into a reoriented arrangement with the average angle between individual fibers and the longitudinal axis of the web increased.

' The cross stretching is efiected in a direction substantially normal to the original direction of fiber orientation while the shrinking is effected in the said original direction of fiber orientation, i.e., the length of the web. This operation results in a deformation of the web in the plane thereof, increasing its dimensions transverse to the direction of the originally parallelized fibers and decreas ing its dimensions in the long dimension.

Changes in web characteristics During this web deformation, the fibers in the web are moved into reoriented positions, but in their new positions they still remain individually intermingled, overlapping and crossing other individual fibers in the web in frictional and mechanical engagement therewith.

-The reoriented web formed by the combined cross stretching and long shrinking operation of the present invention, and then bonded to form a reoriented, nonwoven fabric, brings about in the said fabric an increase in the strength of the fabric in the cross direction (the width), i.e., transverse to the direction of the originally parallelized fibers in the web. In other words, the reoriented web has the potential of being converted by bonding into a nonwoven fabric having an increased tensile strength in the cross direction as compared to the oriented nonwoven fabrics of. the prior art. I

, The term potential tensile strength as applied to a web in the following description refers to the tensile strength of the fabric formed by bonding the fibers of the web into a unitary structure. The cross strength of the fabric is increased to the extent that the originally parallelized fibers in the web are moved or oriented away from the parallel.

. In the reoriented web the density is substantially uniform throughout the area thereof regardless of the thickness of the web or the speed at which it is produced. The preferred reoriented web is one wherein the average angle between individual fibers and the longitudinal axis of the web is increased to the point where the degree of fiber orientation is reduced to approximately 50 percent. A web approaching this preferred form in structure is capable when bonded of providing a long-to-cross tensile strength ratio of approximately one. This preferred web may be called a pseudo-isotropic web, because its Potential tensile strength is of the same general order of.

magnitude in all directions, being in fact substantially equal when measured along the two major axes at 90 to each other, i.e., the longitudinal and transverse axes of the web. Thus, the rearranged fiber web acts very much referred to as a pseudo-isotropic web.

As the fibers of the original oriented web are reoriented to reduce the degree of fiber orientation, the increased width of the web tends to be more or less compensated for by the accompanying long shrinking thereof, with the result that the reoriented pseudo-isotropic web may like a true isotropic web, and ma for this reason be have an area substantially the same as the area of the starting conventional card web. In the preferred'form stretching, so as to keep theweb area and web density substantially constant.

Starting webs Although the machine of the present invention is primarily designed for cross stretching and long shrinking unbonded webs of nonwoven fibers, it can also be used to perform these operations on prebonded nonwoven webs.

The web may comprise natural fibers, such as cotton, wool, jute, ramic, or abaca, or artificial fibers of viscose rayon, cuprammonium rayon, cellulose acetate, nylon, dynel, or other materials, either alone or in combination with one another. The length of the individual fibers depends upon the ultimate purpose for which the web is intended. Regardless of the specific fibers used, the frictional resistance between the individual fibers should be low enough to permit rearrangement of the fibers in the plane of the web without rupture of the web structure.

Apparatus of this invention The machine for cross stretching and long shrinking a web in accordance with the present invention may comprise a feed roll upon which the web is mounted, a wet-out device through which the web is passed, means for simultaneously cross stretching and longitudinally shrinking the web, and a batcher or take-up roll for receiving the web after it has been cross stretched and longitudinally shrunk. Guide rolls are provided between the feed roll and the wet-out device and between the cross stretching means and the batcher or take-up roll.

The wet-out device comprises a pair of nip rolls and a trough containing liquid in which one of the nip rolls is partially immersed to provide liquid for saturating the web. The web is saturated preferably with from 300 percent to 700 percent of water or an aqueous emulsion of a binder such as polyvinyl acetate.

The means for cross stretching and longitudinally shrinking the web comprises a web deforming zone, carrier means for moving the web into and through said web deforming zone, means constraining successive increments of the web into cylindrical surfaces as said web is moved through said web deforming zone, means progressively increasing the dimension of each cylindrical web increment measured transverse to the direction of web travel, means simultaneously decreasing its dimension measured in the direction of web travel, and means for removing the web from the web deforming zone. In this specification and in the claims, the term cylindrical surface means any non-planar surface traced by a straight line, called a generatrix or element, moving parallel to a fixed straight line. The term is not limited "to its frequent, but more restricted, sense of a surface generated (traced) by one side of a rectangle rotated around the parallel side as an axis.

I The web increment is considered as a.relatively short portion of the web having its ends coincident with the opposite edges of the web. In those cases in which the carrier is comprised of a plurality of spaced, individual carrier elements, the dimension of the web increment in the direction of web travel is determined by the spacing of the successive elements of the carrier. The increments each have a dimension in the direction of web travel sufiiciently large that'successive increments of the web may be engaged with a portion of the surface area of successive carrier elements as the web travels through the web deforming zone.

The web deforming zone includes a laterally extensible carrier adapted to move in an endless closed path, means for holding a web in engagement with the carrier for a predetermined portion of its travel, and means for stretchstrips of web of predetermined length, but preferably the material worked on is in the form of a continuous web which is progressively cross stretched and longitudinally shrunk as it is moved with the carrier elements through that portion of the path of travel defined by the curved cam slots which constitutes the web deforming zone.

The structure, by means of which the above-mentioned and other advantages of the invention are attained, will be described in the following specification, taken in conjunction with the accompanying drawings, showing a preferred illustrative embodiment of the invention in which:

Figure 1 is a three quarters perspective view of the machine, looking from the discharge end toward the feed end, With the drive mechanism omitted for clarity, and with a portion of the near pair of cam plates broken away to show the associated slotted ring gear;

' Fig. 2 is a plan view showing the extensible carrier elements in the web deforming zone, with carrier elements stretched and spaced closer to adjacent elements near the discharge end of the machine;

Fig. 3 is a side elevational view of the machine;

Fig. 4 is a plan view of the driving mechanism for rotating the ring gears;

Fig. 5 is a vertical cross sectional view taken substantially along the line 5-5 of Fig. 2, a portion of the near cam plate being broken away to reveal certain details of the construction of the machine;

Fig. 6 is a fragmentary cross sectional view taken substantially along the line 6-6 of Fig. 5;

Fig. 7 is an enlarged fragmentary cross sectional view through one of the cam follower sets showing the relationship between the set of cam followers, the curved cam slots of one of the cam plates, and the associated radial cam slot of the slotted ring gear;

I Fig. 8 is a fragmentary cross sectional view showing the web in engagement wtih the extensible carrier elements at the start of the web deforming zone;

Fig. 9 is an enlarged detail perspective view showing a web being held against one of the carrier elements by the pressure member, with a portion of the web broken away to reveal the structure of the extensible carrier element; and

Fig. 10 is a fragmentary cross sectional View, taken along the line parallel to the extensible carrier element of Fig. 9.

A preferred embodiment of the machine, as shown in the drawings, comprises a base, indicated by the reference number 2, having a standard 3 extending upwardly from each side thereof. Each standard is braced by angle members 4. Opposite ends of a stationary shaft 5 are mounted in suitable supports 6 secured to the top of each standard 3. A key 7 prevents rotation of shaft 5.

A stationary cam 8 is rigidly secured adjacent each end of shaft 5. The cam and related structure, hereinafter described, are the same at both sides of the machine, and therefore only the structure at one side will be described in detail, it being understood that the description applies equally well to the corresponding structure at the opposite side of the machine.

- The cams 8 are angularly disposed in vertical planes which diverge outwardly from the feed end of the machine at equal angles. The cams may have any desired angularity, depending upon the amount of cross stretching desired and the other factors, such as the maximum radius of the cams, the axial spacing between cams, and the extent of travel of the web through the web deforming zone, which affect the percentage of cross stretching of the web. The divergence of the opposing cam. plates, the design of the curved cam slots in the plates, and the spacing between the two pairs of cam plates govern the percentage of cross stretch obtained by use of the machine. In the illustrated embodiment, each of the extensible carrier elements is stretched to double its length from the beginning of the web deforming area to the output end thereof, so that the web will be cross stretched percent of its original width.

Each cam comprises an inner cam plate 9 and an outer cam plate 10, best seen in Fig. 6. Cam plate 9 is secured at its inner edge to an annular plate 11 which encircles shaft 5 and is secured thereto by a screw 12. A sleeve 13, secured against rotation around shaft 5 by key 7, abuts plate Ill and has an integral flange 14 spaced at predetermined distance from plate 11 and extending parallel thereto. Sleeve 13 is provided with a plurality of fins or webs 15 to reinforce flange l4. Cam plate 10 is secured at its inner edge to flange 14-. The outer edges of cam plates 9 and 10 have a spacer 16 interposed therebetween to keep the cam plates parallel to each other. The outer edges of cam plates 9 and 16 are secured together by bolts which extend through spacer 16. A bracket 1t? secured to one of the angle members 4- is secured to cam plate 10 to help support the outer portion of said cam plate.

Cam plates 9 and 10 are provided with duplicate endless cam slots 17 which provide a closed path of travel for the cam followers hereinafter described. The cam slots may be of any suitable shape, but must be eccentrically arranged relative to the cam plates, as explained in more detail below. For a given plate setting, i.e., angle and spacing, the exact shape of the cam slot controls the amount of cross stretching and longitudinal shrinking of the web, as will be explained more fully hereinafter. The cam slots actually divide each cam plate into two sections which are held together by plurality of brackets 18 spanning the cam slot in cam plate 10, and by the bolts extending tln'ough the outer edges of the cam plates and the spacer 16.

A circular plate 19 is rotatably mounted between each pair of cam plates. In the embodiment shown, plate 19 is provided with gear teeth on its periphery to form a ring gear.

The driving mechanism for rotating both ring gears is shown in Figs. 2 and 4. A motor 20 mounted on base 2 has a speed reducer 21 coupled therewith to drive a pulley 22. A belt 23 connects pulley 22 with a pulley 24 mounted on a drive shaft 25. Bevel gears 26, mounted on shaft 25, mesh with bevel gears 27 to rotate gears 28 (Fig. 5), each mounted on a short shaft 29 on which gear 27 is mounted. Gear 28 is meshed with ring gear 19 to rotate it. An annular bushing 3d (Fig. 6), positioned between cam plates 9 and lit), engages the inner edge of ring gear 19. Thrust bearings 31 rotatably mounted in cam plate 9 engage one side of ring gear 19 near its outer edge to help maintain alignment of the ring gear. In Fig. 4, for purposes of clarity, cam plate 9 and outer cam plate 10 of the stationary cams 8 are shown in phantom only, and plates 11 and flanges 14 are omitted altogether.

Each ring gear 19 is provided with a plurality of radial cam slots 32 each of which is long enough 'to intersect cam slot 17. At the edge of the ring gear closest to the feed mechanism, hereinafter described, the curved cam slot 17 intersects radial cam slots 32 near their outer ends. As the curved cam slot extends towards the opposite edge of the cam plate, the point of intersection with each successive radial cam slot moves closer to the inner, converging ends of the radial slots. Thus, as an inspection of Fig. 5 shows, the distance between adjacent pairs of said points of intersection decreases as the curved cam slot extends towards the output end of the machine. The importance of this arrangement will be hereinafter discussed in connection with the longitudinal shrinking of the web.

A set of cam followers 33 is associated with curved cam slot 17 at each intersection with the radial cam slots 32. Each set of cam followers comprises round cam followers 35 and 36 engaged with curved cam slots 17 in cam plates 9 and 10, respectively, and an intermediate rectangular cam follower 37 engaged with radial cam slot 32;, Pin 34.,- extends from-"the? iunerr end; of. rounds cam. follower-.35 Reetangulancamiollower =37. is; sepavrated from cylindrical cam follower s;35 and:36; byplates 3.8,. Roundicam followers; 35; and;\3.6, may be; rigid with pin; 35.. or; may be. rotatable Plates; 38; are; preferably rectangular, V andv are sul'ficiently wide to traverse; radial; slot 32,. to prevent displacement of the. cam: follower; per.-

pendieular to the slotted cam gear, andthusinsureproper. registration, of the respective cam followers. with both. curved.cam slots 17 andradial cam tslot32.

Each. pin 34 has; a coupling 39; pivotallyi secured to its .inner.,end-to secure opposite; ends of carrier elements 40. to the cam followers. Each carrier, element 413.com? prises, a longitudinally extensible coil spring having op posite ends each secured to a coupling 39. Asshown in Big 6,,the-pivotal connection;ofi'the coupling member 39 with. pin; 334. permits; the 1 coupling;- member to be aligned with the; carrier element. in: any; position of A the-carrier element: as the. set. of earn followers is; moved: through-- out .-the-; path of cam. slot-,1 7, and thereby protects the 1 coupling members; against excessive; strain.

Assho wnin Fig, 9, the; outer) surfaoetof eaoh. spring or carrier element 40 is knurledonroughened, as indicated at. 41, to enhance; the frictional; contact; between the web. 42 of fibrous nonwoverrmaterial and the carrier: elements, and thereby prevent the webffrom slipping relativeto. the carrier. elements as the; carrier. elements .are moved; by, the-cam followers through the web, deform-ingzoue during the rotation of theslotted; ring; gear;

A:. more positive frictional contacfti is; provided: adjacent. the; longitudinal edges; Ofthe: web by; a. pressure member 43=-. which is secured to the inner: surfaeezofi each cam, plate 9.by means ofa bracket 44: (Fig: 1')'. Pressure member. 4&is a brush-likemember comprising abacking: 45. of. any suitablestifimaterial, curved to conformto thecurvatureof the adjacentrportion: of: camislotc 17, and provided-with needlesfllfi adapted to press the edges of thewebinto-firm frictional engagement with the carrier. elements, The lower portions, of; the needles: arebentslig tly away from direction of; travel of web, as. indicated at 47,, to prevent" the needles, from. tearing: or; ripping the-edgesiof; the web as his fedinto engagement with thecarrier elements,

As; seen. in Figs. 1 and; 3311161 means; for feeding. the fibrous,- nonwoyen web to the; carrier comprises a: feed roll .48,, two-guide; rolls 4 and; 50, a Wet-out device- 51; and another. guide roll152. Feed-101148 is mounted for. free rotation in a cradle; 53% supported at; the top.-.

of two standards 54 projectingupwardly from base 2. Guide rolls 49 and So are mounted for free rotation in suppor membersss built-up in any-suitablelmanner from base; 2 The.wet-o-ut? device; 5-1 and: guide; roll; 52: are; supported by members 56; also proj ecting: upwardly from; baseszt The.we t-out device, comprises; upper. andlowernip rolls;..57-and 58, respectively, and apan 59 for containing water or an aqueous emulsion-of; a binder, ,suchas .poly.. vinyl acetate,- in which the" lower nip roll 58, is partially immersed. Nip-rollSS; is driven by a belt 60through a pulley 66' (Fig. 4) on; a-shaft filmounted; imbearings: 61,. A belt 62' extending: around a pulley. 63 mo.unted on. shaft drives shaft 61., through a second pulley 63 mounted on shaft 61.

After theweb 42 is; fed from th$,fdf1'01lf 48,-it passes. through the wet-on devicewhere-it issaturated'preferably with from 700 percent to 1,500 percentoff-water, or, whatever other liquid is kept inpan 59; The wet.-

' out? device shown is conventionahand." any othensuitablemeans. for saturating the. web; to the, desired extentmay be used. The saturated web. passes under guide roll. 52 and then is engaged betweenone of the, carrier elements and the pressure members 43 at the feed end, of theweh deforming zone of the carrier.

The process of cross stretching and simultaneously longitudinally shrinkingthe web is preferably continnops,

2 One. complete revolution. both ends of eachcarrier elementmust move through. a complete rotation of 360 Eaclr, setof; cam. followers. is also engaged, through round cam followers 36 andi,'. with curved cam slots '17 and is therefore. restricted. in said movement of 360 to the closed; path of -travel defined' by thetcurved cam slots;

The angularity' of cams. 8 causes each of the carrier elements.- to be stretched and: contracted duringsuccessivei halfj revolutions of-the ring gears; The-successivecar =1 rien elements-are contractedasrtheysmove from theout-- put end: of:;the= carrier tothefeed end, at'which end-theyare of; minimum length. Eachweb; increment is engaged:

with :an extensible carrier element at onarljacent the point;

of; length of the. latter, which approxim ately the same length as the initialwidth of the fibrous, nonwoven. web, and its: outer. edges are positioned between the: pressure: members: 43: and: the carrienelement; Web= increment Alibounded by=-planes AA. andBBi (seen in: SGCIiOIlglIl' Fig. 8); is-ishown. in. the position-it occupies justaftenit, has become engaged with: a carrien'elernent: 44L Webdncrement-BC, also seenin-Fjg; 8, hasmoved on :intothe web deforming zone, having become engaged amoment before; with the preceding carrier element:40.=

As seen-from Fig.v 8, each. such web incrementeformsa; cylindrical surface as:v defined above; Specifically, in: the embodiment-shown. eachsurface; has. a. cross-sec tionv in thexshapei'of-a shallow V-with arounded bottom.

ed;portion ofthis cylindrieali surface is that part ofgthe web-increment which. is in contactwith thecarrier element; portion is. flankeda by. twoistraight' sections. corresponding? to, the slanting members ofrtheshallow letter \I..

As; the. rotation of the ring; gears; moves each. carrierelement. along; itsclosed path of: travel, the=carrierel'e ment; andzthe; increment of! the webin engagement there with, are; stretched, in; the direetioni normal to: the webtravel. Successive. web increments become engaged with the; successive .carrier elements. as they reachthe feed end. of the: carrier; so that thecarrien elements and theweh move; in, asubstantially; continuous. process. Webin crements NQ,,MN,1and.LM,-' shown in Fig. 1, areexamples; of web increments. that have become: engaged: with successive; carrien elements. 40. and; arebeingmoved:- through the web deforming zone; The; extent of travel; of theswebwith thecarrier ele ments dependsilargely upon thelength: of lpressure mem.-. ars 43;. Rreferably x the, pressure members: 43* extend approximately 180 of the closed path. of" travel defined" by curved: earn. slots 17'. During this movement the stretching of; the; carrierelements and the: web is:progressiye and reaches; its maximum: attheend of 180 of travels. The=portion of'=the: closed path-.of'ftravehof the arrier: elements: between: the feed and output ends; of the oaimen constitutes tine-web. deforming zone, with the feed nd. and output end: at that: zone coinciding; with thecorresponding; ends; of: the carrier.

S; the: Web; is; stretchedJtransversely, the shape, of-

' ouryedcam slots ll'forceswthecam follower sets-to move closer" to: the; inner end of theconverging radial cam slots 32; in the ring: gears? This movement-of the cam followers: 7 decreases: the; longitudinal distancebetween adjacent carrier: elements: and: the web; increments ene sed therewith, -a n d;,thereby,shrinksztheaweb longitudinal.- ly as it is cross; stretched. The;angulanityiofi he cam-athe, axial d nce; etwe nzthe ams, and: the shape tlth cam-slot. are, designed, as v explained above, to maintain o stant; ensity. or. nit.- w i h hmush ut the. reaof he. We

The web. may e. removed f om he. carr er. telut n iut ey ud the. ndf the.nressureamembers te. Bren,

erably, the web is removed from the carrier at a point approximately 180 from the feed end so as to obtain the maximum stretch and the maximum long shrink- :age. However, if the angularity of the cams is increased, or the radius of the curved cam slot is increased, the web may be removed from the carrier at a point less than 180 from the feed end and still be stretched to the same extent as in the preferred embodiment.

As shown in Fig. 3, after the web is separated from the carrier it is passed loosely under a guide roll 64, over a guide roll 65, and then to a take-up or batcher roll 66. Guide roll 65 is mounted in standards 67 projecting upwardly from base 2. A pair of angle irons 68 secured to the rear end of base 2 support batcher roll 66 in open ended notches 69 extending downwardly from the upper end of each angle iron 68. Another roll 70 is mounted in bearings 70 provided in angle irons 68 just below the bottom of notches 69. The notches permit roll 66 to rise as the web winds around it. Roll 70 has the same diameter as roll 65.

It is desirable to provide slack in the Web between the output end of the carrier and the take-up or batcher roll 66 to avoid any draft that would stretch the web longitudinally and tend to nullify the longitudinal shrinkage. The slack in the web is best seen in the vicinity of guide roll 64 in Figs. 3 and 5. The slack is maintained by driving the rolls 65 and 70, in a manner hereinafter described, at a circumferential rate of speed equal to the linear speed of discharge of the web from the carrier.

The drive mechanism for rolls 65 and 70 is shown in Fig. 2. A pulley 71 mounted on drive shaft 25 transmits the rotation of shaft 25 to another shaft 72 through a .belt 73 and a pulley 74 mounted on the latter shaft. Shaft 72 has a gear 75 meshed with another gear 76 mounted on a short shaft 77. A belt 78 extending around a pulley 79 on shaft 77 and another pulley 80 on the shaft 81 of roll 65 drives the latter roll. The relationships of the gears and pulleys just described make the circumferential speed of roll 65 match the linear speed of the web as it is discharged from the carrier. More over, a belt 82 extending around similar pulleys on the shafts of rolls 65 and 70 drives the latter roll at the same angular and circumferential rates as roll 65. The weight of roll 66 and the web carried thereby resting on roll 70 is sufficient to cause roll 66 to rotate with the rotation of roll 70, and thereby wrap the cross stretched and long shrunk web around it at the same linear speed at which the web comes off the carrier. Thus, the amount of slack under guide roll 64 remains unchanged.

A housing 83 is provided at one side of the machine to enclose the drive mechanism. A dust guard 84 is provided for the ends of rolls 64 and 65 at the opposite side of the machine.

In the operation of the cross stretching machine described, the movement of a given carrier element from the feed end of the carrier moves the next carrier element into the feed position, and pulls the next web increment into engagement with said second carrier element and the pressure members. f As each successive increment of the web engages a carrier element moved to feed position by the movement of the carrier along the closed path defined by the curved cam slot, the web is continuously moved with the carrier elements through a predetermined portion of said path which constitutes the web deforming zone. The pressure members extend around a portion of the path of travel, preferably slightly less than 180, and the web. is separated from the carrier elements at the output end of the web deforming zone, which is preferably adjacent the end of the pressure members.

The carrier elements are of minimum length at the feed end of the carrier and are progressively stretched, in a direction normal to the direction of web travel, at a predetermined rate until they reach their maximum length at or adjacent the output end of the carrier. The knurled surfaces of the carrier elements and the pressure members engaging the outer edges of the web cause the web to be cross stretched along with the carrier elements throughout the Web deforming zone.

As the carrier elements are moved from the feed end to the output end of the web deforming zone, the spacing between adjacent carrier elements is progressively decreased to long shrink the web simultaneously with its cross stretching. The curved cam slot is so designed, relative to the angle of divergence of the cams and the axial spacing between the cams, that the desired percentage of cross stretching is obtained, and the longitudinal shrinking of the web is controlled in relation to the cross stretching, so that an approximately constant density or unit web Weight is maintained throughout the area of the web.

The travel of the web through the web deforming zone of the carrier, i.e., from the feed end to the output end, efiects an important change in the orientation of the individual fibers of the web. At the feed end of the web deforming zone, the degree of fiber orientation in a card web is commonly about 70 percent to percent 'in the longitudinal direction. As the Web moves through the web deforming zone, the orientation of the fibers is changed and the fibers are gradually moved towards transverse orientation. The individual fibers do not move abruptly from one direction to the other, but move gradually in accordance with the extent to which the web has been stretched. The change in direction of most of the fibers is consistent and uniform as the cross stretching proceeds. The frictional resistance between the individual fibers of the saturated web is low enough to permit rearrangement of the fibers in the plane of the web without rupture of the web structure. Since the transverse pull is spread evenly over the Whole web, no portion of the web is subjected to strain sufficient to tear it.

Although the cross stretching may be continued until the fibers are generally oriented more in a transverse than in a longitudinal direction, it is preferred'to limit the stretching to a point where the degree of fiber orientation is approximately 50 percent, as this arrangement provides maximum potential tensile strength for the Web.

While we have described a preferred embodiment of the invention in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather than restrictive, as many details may be modified or changed without departing from the spirit or scope of the appended claims. Accordingly, we do not desire to be restricted to the exact details of construction or method described.

We claim:

1. A method of cross stretching and longitudinally shrinking a nonwoven web comprising a major proportion of oriented textile fibers, individual fibers of said Web having frictional resistance therebetween low enough to permit rearrangement of said fibers in the plane of the web without rupture of the Web structure, which comprises: saturating said web with water, advancing said saturated web into a web deforming zone With the oriented fibers in the web in the direction of travel, constraining successive increments of the advancing web into cylindrical surfaces, the axes about which said surfaces are traced extending transversely of the direction of travel of the Web, moving the Web so constrained through the web deforming zone, while progressively increasing to a predetermined figure the dimension of each successive cylindrical web increment measured transverse to the direction of web travel and simultaneously decreasing to a predetermined figure its dimension measured in the direction of web travel, and removing the Web from the output end of the web deforming zone when it has been cross stretched and longitudinally shrunk to the predetermined figure.

2. A cross stretching apparatus comprising a carrier consisting of a plurality of spaced, parallel, extensible carrier elements, rotatable means for moving said carrier engagement with' one of said-carrier elements: at said feed: 7

end, means for progressively: stretching; said carrier. ele,-- mentsin 1 adirection transverse to the direction of: web travel -as they are moved throughsaid webzdeforming, zone,-means for holding said; web in engagement-with said carries; elements as said carrien elements are moved throughsaid-webdeforming zone, wherebysaid web is progressively" cross stretched as it is movedthrough said web-deforming zone, means-for shrinking saidtweb longi-- tudinallyv as it is moved through saidweb deforming zone, and means toremove said web from saidcarrier at-the output end of-said web deforming zone 3v A cross stretching apparatus comprising, a carrier consistingiof a; plurality of spaced,;parallel coillsprings, having roughened outer surfaces, rotatable means:- formoving saidcoil springs in a closed path eccentric to. theaxisofrotation of said rotatable means, a portion of said closed path constituting a web deformingtzonethauing, a feeda end and anoutput end, means for moving a nonwovenweb into engagementwith the roughened surfaceof one'of said coil springs at said-feed end, means for progressively stretching said: springs in a direction transverse to the direction of web travel. as they are moved: through said web deformingzone, means for hold, ingtsaidweb inengagement with said coilsprings as. said springsare moved through said web deforming: zone,

whereby saidweb is progressively cross stretched at it is; moved" through said web deforming-zone, means for shrihkingsaid web longitudinally as it ismoved: through saidvveb deformingzone, and means. to remove saidiweb. horn said oarri'er at the output end ofsaid web deforming zoner 4'. 'A cross stretching apparatus comprising a carrier consisting of a plurality of spaced, parallel coilv springs having roughened outer surfaces, rotatable means: for moving said coil springs in a closed path eccentric to the of rotation of said" rotatable means, a portion of said closed path constituting a web deforming zone having a feed end and an output end, means for moving a nonwoven web into engagement with one of said' coil springs at said feed end, means for stretching each of said a coilsprings in-ua direction transverse to the direction of Web travel as it is moved through said web deforming zdne, pressure means to hold said web in engagement tlie' rou hened surface of said coil springs as said spring are moved through said web deforming, zone, whereby" said web. is progressively cross stretched as it is moved through said web deforming zone, means for. shrinking said'web longitudinally as it is moved'through said web deforming zone, and means to remove said web nemsaid carrier at the output end of said web deforming zone.

5. A cross stretching apparatus comprising a carrier cdnsisti'ng'of a plurality of spaced, parallel carrier elements, a cam. positioned on each side of said carrier, said c'anis having duplicate cam slots, a plurality of cam fdllower'sin each' of said cam slots, rotatable means for moving said carrier elements in a closed path defined by said slots, said cam slots being eccentric to the axis of rotation of said rotatable means, a portion of said closed path constituting a web deforming zone having a fed end and an output end, said cams diverging from each other from said feed end to said output end, means for moving a nonwoven web into engagement with one of said carrier. elements at said feed end, each of said carrier elements. having its opposits ends secured to one of said cam followers, whereby said carrier elements are stretched in a direction transverse to the direction ofweb travel as they are moved through said Web deforming Zone, means to hold said web in engagement with, saidi carrier elements, as said'carrier elements are" moved'through said.v web deforming zone, whereby; said web: is, progressively cross stretched with said carrier elements as it is moved through said web deforming zone,;

means for shrinking said web longitudinally as it is-moved.

through said-web deforming zone, and means to remove:

consisting of a plurality of spaced, parallel carrier elements, rotatable means for: moving said carrier elements in a: closed patheccentric to the axis oftrotation of-'said-= rotatabletmeans, a portion of said closed path, COIlSiit' tutin'g, aweb deforming zone having a feed endandzan. output end,- means for moving a nonwoven web:into,en,

gagementvwith one of said carrier elements: atsaid feed end, means for stretching, said: carrier elements: in a: direction transverse to the direction of web travel asithey, are moved through said web deformingzone, the eccentricity; ofsaid closedtpath causing said: carrier elements,

to..move.-into closer spacing as they are moved through: said web. deforming zone, means to hold said web in:

engagement with, said carrier elements as said carrier elements are moved through said web deforming, zone,,

whereby said web is progressively cross stretchedand, longitudinally shrunk as it is moved through, saidwebj deformingzone, andmeans to remove said web frorntsaid carrier at .the output end of said Web: deforming; zone.

7.- A cross stretching apparatus comprising, a carrier consisting. of a plurality of spaced, parallel, extensiblev carrier elements, a cam positioned on each sideof said carrier, said cams having duplicate cam slots, a. plurality.- ofwcamifollowers in each of said cam slots, rotatable means for moving said carrier elements in a closed path, defined by said cam slots, said cam slots being eccentric to the axis of rotation of said rotatable means, a portion of said closed path constituting a web deforming zone having a feed end and an output end, said cams diverging,

from each other from said feed end to said output end, means for moving a nonwoven web into engagement with one of said carrier elements at said feed end, each of, said carrier elements having its opposite ends secured to one of said cam followers, whereby said carrier elementsv are stretched in a direction transverse to the direction, of web travel as they are moved through said web deforming zone, the eccentricity of said closed path causing said carrier elements to move into closer spacing as they are moved through said web deforming zone, -means, to.

hold said web in engagement with said carrier elements as said carrier elements are moved through said web deforming zone, whereby said web is progressively cross, stretched and longitudinally shrunk as it is moved through said web deforming zone, andmeans, to remove: said web,

from saidcarrier at the output end of saidweb deforming zone;

8'; An apparatus for cross stretching a. nonwoven web, comprising a carrier, means for moving said carrier-inlet closed path, means for holding a web in engagement with said carrier during movement of said carrierthrough a predetermined portion of said closed path, said carrier comprising a series of spaced, parallel carrier elements eachextensible in a direction transverse to the direction of web travel, means for progressively stretching each of said carrier elements in a direction transverse to the. direction of web travel as said carrier is moved through said predetermined portion of said closed path, means.

for simultaneously moving said carrier elements into closer carrier elements, said carrier having a web deforming" zone having a feed end and an output end, means to i move said carrier elements through said web deforming zone, means. to. move a web into engagement w-itlnsai'd carrier elements, means to stretch each of said carrier elements in a direction transverse to the direction of travel of said carrier elements as they are moved between the feed end of said web deforming zone and the output end thereof, means to hold said web in engagement with said carrier elements during movement of said carrier elements through said web deforming zone, and means to move said carrier elements into closer spacing to shrink said web longitudinally as it; travels through said Web deforming zone.

10. A cross stretching apparatus comprising a carrier consisting of a plurality of spaced, parallel, extensible carrier elements, a cam positioned adjacent opposite sides of said carrier, each of said cams having an identical endless cam slot, a portion of said cam slots defining a web deforming zone having a feed end and an output end, a plurality of cam followers in each of said slots, one of said cam followers being secured to one end of each of said carrier elements, means to move a web into engagement with said carrier elements, means to move said cam followers along said cam slots, means to move said carrier elements into closer spacing as their associated cam followers are moved through the portion of the cam slots defining said web deforming zone, means for progressively stretching said carrier elements as they are moved through said web deforming zone, means to hold said web in engagement with said carrier elements during movement of said carrier elements through said web deforming zone, whereby said web is simultaneously cross stretched and longitudinally shrunk, and means for removing said Web from said carrier elements at the output end of said web deforming zone.

11. An apparatus for simultaneously crossstretching and longitudinally shrinking a nonwoven web comprising a pair of cams in diverging angular relationship, each of said cams having an endless curved cam slot, a plurality of cam followers in each of said curved cam slots, a rotatable plate juxtaposed against each of said cams, means for rotating said plates, said plates being engaged with said cam followers to move said cam followers along said cam slots as said plates are rotated, an endless series of carrier elements, each of said carrier elements having its opposite ends each secured to one of said cam followers, means for moving successive web increments into engagement with successive carrier elements as said carrier elements are moved by said cam followers, means for stretching each of said carrier elements in a direction transverse to the direction of web travel as said carrier elements are moved through a predetermined portion of their travel, said predetermined portion of the travel of said carrier elements comprising a web deforming zone having a feed end and an output end, means for maintaining said web increments in engagement with said carrier elements as said carrier elements are moved through said web deforming zone, whereby said successive web increments are stretched transversely of the direction of web travel as they are moved through said web deforming zone in engagement with said carrier elements, means for moving said carrier elements into closer spacing as they approach the output end of said web deforming zone to shrink said web longitudinally during the transverse stretching thereof, and means to remove said web increments from said carrier elements at said output end of said web deforming zone.

12. An apparatus for simultaneously cross stretching and longitudinally shrinking a nonwoven web comprising a pair of cams in diverging angular relationship, each of said cams having an endless curved sam slot, a plurality of cam followers in each of said curved cam slots, a rotatable plate juxtaposed against each of said cams, means for rotating said plates, said plates being engaged with said cam followers to move said cam followers along said cam slots as said plates are rotated, an endless series of carrier elements, each of said carrier elements having its opposite ends each secured to one of said cam followers, means for moving successive web increments into engagement with successive carrier elements as said carrier elements are moved by said cam followers, means for stretching each of said carrier elements in a direction transverse to the direction of web travel as said carrier elements are moved through a predetermined portion of their travel, said predetermined portion of the travel of said carrier elements comprising a Web deforming zone having a feed end and an output end, means for maintaining said web increments in engagement with said carrier elements during movement of said carrier elements through said web deforming zone, whereby said successive web increments are stretched transversely of the direction of web travel as they are moved through said Web deforming zone in engagement with said carrier elements, said cam slots being shaped to force said carrier elements into closer spacing with adjacent carrier elements as they approach the output end of said web deforming zone, whereby said web increments are longitudinally shrunk simultaneously with said transverse stretching thereof, and means to remove said web increments from said carrier elements at the output end of said web deforming zone.

13. An apparatus for simultaneously cross stretching and longitudinally shrinking a nonwoven web comprising an enless series of extensible carrier elements movable in a closed path, means for moving said carrier elements through said closed path, means for moving successive web increments into engagement with successive carrier elements during movement of said carrier elements, means for stretching each of said carrier elements in a direction transverse to the direction of web travel as said carrier elements are moved through a predetermined portion of said closed path comprising a web deforming zone having a feed end and an output end, means for maintaining said web increments in engagement with said carrier elements during movement of said carrier elements through said web deforming zone, whereby said successive web increments are stretched transversely of the direction of web travel as they are moved through said web deforming zone in engagement with said carrier elements, means for long shrinking said web increments as they are moved with said carrier elements through said web deforming zone, and means to remove said web increments from said carrier elements at said output end of said web deforming zone.

14. A cross stretching apparatus comprising a series of spaced, parallel extensible carrier elements mounted for movement along a closed path, means for moving successive carrier elements along said closed path, means operable to stretch said carrier elements as they are, moved from an initial position in said closed path to a second position in said path removed from said initial position by approximately said carrier elements .being of minimum length at said initial position and of maximum length at said second position, the portion of said closed path between said initial and said second position constituting a web deforming zone, means for moving an increment of a nonwoven web into engagement with a carrier element at said initial position,

means for holding said web increment in engagement with said carrier element as said carrier element is moved through said web deforming zone, whereby said web increment is cross stretched progressively with said carrier element, means for moving said carrier elements mto closer spacing as they approach the output end of said web deforming zone to shrink said web increment of spaced, parallel extensible carrier elements mounted for movement along a closed path, means for moving successive camel elements along said closed path in predetermined relationship, means operable to stretch said carrier elements as they are moved from an initial position in said closed path to a second position in said closed path removed from said initial position by approximately 180, said carrier elements being of minimum length at said initial position and of maximum length at said second position, said carrier elements being spaced apart a greater distance adjacent said initial position than adjacent said second position, the portion of said closed path between said initial position and said second position constituting a web deforming zone, means for moving successive increments of a nonwoven web into engagement with successive carrier elements as said successive carrier elements are moved into said initial position, means for holding each of said web increments in engagement with its carrier element as said carrier elements are moved through said web deforming zone, whereby each of said web increments is progressively cross stretched and longitudinally shrunk simultaneously in said web deforming zone, and means for removing said successive web increments from said carrier elements at said second position.

16. A cross stretching machine comprising a plurality of extensible carrier elements, means for holding a fibrous nonwoven web ,in engagement with said carrier elements, a cam positioned adjacent each end of said carrier elements, said cams being fixed in diverging relationship, a rotatable ring gear juxtaposed against each of said cams, each of said cams having an endless curved cam slot eccentric to said juxtaposed ring gear, each of said ring gears having a plurality of radial cam slots, each of said radial slots intersecting the curved cam slot of the adjacent carn, a set of cam followers secured to one end of each carrier element, said set comprising a first cam follower engaged with each of said radial cam slots and a second cam follower associated with the first cam follower and engaged with the curved cam slot intersected by said radial slot, said curved cam slots being shaped to force said carrier elements into closer spacing with adjacent carrier elements as they approach the output end of said web deforming zone, means to rotate said ring gears at the same rate, whereby said carrier elements, with said web in engagement therewith, are moved in a closed path defined by said curved cam slots, and means for removing said web from said carrier elements at a pre determined point in said closed path of travel.

17. A cross stretching apparatus comprising a pair of vertically disposed earns, a rotatable ring gear juxtaposed against each of said cams, means for rotating said ring gears at the same rate, each of said cams having an identical endless curved cam slot, a plurality of cam followers mounted in spaced relationship in each of said curved cam slots, said cam followers being connected to said ring gears, whereby said cam followers are movable in said cam slots by rotation of said ring gears, a series of spaced,- parallel coiled springs, each of said springs having its opposite ends secured to a cam follower in each of said curved cam slots, whereby said springs are moved through a closed path defined by said cam slots as said ring gears are rotated, a portion of said closed path constituting a web deforming zone having a feed end and an output end, said camsdiverging from said feed end to the output end of said web deforming zone, whereby said springs are stretched as they are moved through said web deforming zone, means for engaging a nonwoven web with the surface of a spring positioned at said feed end, a pressure member mounted on each of said cams adjacent said cam slots, said pressure member comprising a backing and a plurality of closely spaced needles engageable with said web to hold it in against the surface of said spring, said pressure members being shaped to conform to the curvature of said cam slots and extending from said feed end to said output end to permit removal of said web from said spring at said output end, and said curved cam slots being shaped to cause said springs to move into closer spacing as they are moved through said web deforming zone, whereby said web is simultaneously cross stretched and long shrunk as it is moved through said web deforming zone.

18. A cross stretching apparatus comprising a pair of vertically disposed cams, a rotatable ring gear juxtaposed against each of said cams, means for rotating said ring gears at the same rate, each of said ring gears having a plurality of radial slots extending approximately from its center to its outer edge, each of said cams having identical endless curved cam slots, each of said radial slots intersecting the curved cam slot of the adjacent cam, a plurality of sets of cam followers mounted in said radial and curved cam slots, each of said sets comprising a first cam follower engaged with one of said radial slots and a second cam follower associated with the first cam follower and engaged with the curved cam slot at its intersection with said one radial slot, whereby said camfollowers are movable in said cam slots by rotation of said ring gears, a series of spaced, parallel coiled springs, each of said springs having its opposite ends secured to a cam follower in each of said cam slots, whereby said springs are moved through a closed path defined by said cam slots as said ring gears are rotated, a portion ofsaid closed path constituting a web deforming zone having a feed end and an output end, said cams diverging from said feed end to the output end of said web deforming zone, whereby said springs are stretched as they are moved through said web deforming zone, means for engaging a nonwoven web with the surface of a spring positioned at said feed end, a presusre member mounted on each of said cams adjacent said cam slots, said pressure member comprising a backing and a plurality of closely spaced needles, the lower portion of each of said needles being bent slightly away from the direction of web travel and engageable with said web to hold it in against the surface of said spring, said pressure members being shaped to conform to the curvature of said cam slots and extending from said feed end to said output end to permit removal of said web from said springs at said output end, and said' curved cam s'lots being shaped to cause said springs to move into closer spacing as they are moved through said web deforming zone, whereby said web is simultane ously cross stretched and long shrunk as it is moved through said web deforming zone.

19; A cross stretching apparatus comprising an extensible carrier, rotatable means for moving said carrier, means for confining said moving carrier in a closed path eccentric to the axis of rotation of said rotatable means, a portion of said closed path constituting a web deform ing zone having a feed endand an output end, me'ans for moving a nonwoven web into engagement with said carrier at said feed end, means for progressively stretching said carrier in a direction transverse to the direction of web travel as the carrier is moved through said web de-' forming zone, means for holding said web in engagement with said carrier as the latter is moved through said .web deforming zone, whereby said web is progressively cross stretched as it is moved through said web deforming zone, means for shrinking said web longitudinally as it is moved through said web deforming zone, and means to remove said web from said. carrier at the output end of said web deforming zone. I v

20. A cross stretchingapparatus comprising, a carrier consisting of a succession of extensible elements, a cam positioned on each side of said carrier, saidcams having duplicate cam slots defining a closed curved path, a plurality of'ca'm followers in each of said cam slots, rotatable means for moving" said succession of carrier elements said closed c'am path defined by said cam slots, said cam slots being eccentric to the axis" of rotation of said r0 tatable means, a portion of said closed path constituting a web deforming zone having a feed end and an output end, said cams diverging from each other from said feed end to said output end, means for moving a nonwoven web into engagement with said carrier at said feed end,

each of the elements comprising said carrier having its opposite ends secured to one of said cam followers whereby said carrier is stretched in a direction transverse to the direction of web travel as the carrier is moved through said web deforming zone, means to hold said Web in engagement with said carrier as the latter is moved through said web deforming zone, whereby said Web is progressively cross stretched with said carrier as it is moved through said Web deforming zone, means for shrinking said web longitudinally as it is moved through said web deforming zone, and means to remove said Web from said carrier at the output end of said Web deforming zone.

21. An apparatus for simultaneously cross stretching and longitudinally shrinking a nonwoven web comprising an extensible carrier, rotatable means for moving said carrier, means for confining said moving carrier in a closed path, a portion of said closed path constituting a web deforming zone having a feed end and an output end, means for moving at least a portion of each of successive increments of a nonwoven web into engagement with said carrier at said feed end, said moving carrier constrain ing into cylindrical surfaces said successive increments of the advancing web as they become engaged with said carrier, the axes of said cylindrical surfaces extending transversely of the direction of travel of the web, means for progressively stretching said carrier in a direction transverse to the direction of web travel as the carrier is moved through said web deforming zone, means for simultaneously progressively decreasing the dimension of each successive cylindrical web increment measured in the direction of Web travel, whereby said web is progressively cross stretched and long shrunk as it"is moved through said Web deforming zone, and means for removing said web from said carrier at the output end of said web deforming zone. V

22. A cross stretching apparatus comprising a carrier consisting of a plurality of spaced, parallel, extensible carrier elements, said carrier having a Web deforming zone having a feed end and an output end, means to move said carrier elements through said web deforming zone, means to move a web into engagement with said carrier elements, means to hold said web in engagement with said carrier elements during movement of said carrier elements through said web deforming zone, means to stretch each of said carrier elements at a predetermined rate in a direction transverse to the direction of travel of said carrier elements as they are moved between the feed end of said web deforming zone and the output end there of, and means to move each of said carrier elements closer to the immediately preceding carrier element at a predetermined rate as the elements pass through said web deforming zone so as to shrink said web longitudinally as it travels through said zone. g

23. A cross'stretching apparatus comprising a carrier consisting of a plurality of spaced, parallel, extensible carrier elements, a cam positioned on each side of said carrier, said cams having duplicate cam slots, a plurality of cam followers in each of said cam slots, rotatable means for moving said carrier elements in a closed path defined by said cam slots, said cam slots beingeccentric to the axis of rotation of said rotatable means, a portion of said closed path constituting a web deforming zone having a feed end and an output end, said cams diverging from each other from said feed end to said output end, means for moving a nonwoven web into engagement with one of said carrier elements at said feed end, each of said carrier elements having its opposite ends secured to one of said cam followers, whereby said carrier elements are stretched in a direction transverse to thedirection of Web 20 s s s travel at a predetermined rate as they are moved through said web, deforming zone, the eccentricity of said closed path causing said carrier elements to move into closer spacing at a predetermined rate as they are moved through said web deforming zone, means to hold said web in engagement with said carrier elements as said carrier elements are moved through said web deforming zone, whereby said web is progressively cross stretched and longitudinally shrunk as it is moved through said web deforming zone, and means to remove said web from said carrier at the output end of said web deforming zone.

24. A method of cross stretching and longitudinally shrinking a nonwoven web comprising a major proportion of oriented textile fibers, individual fibers of said web having frictional resistance therebetween low enough to permit rearrangement of said fibers in thep'lane of the web without rupture of the Web structure, which comprises: saturating said web with water, advancing said saturated web into a web deforming zone with the oriented fibers in the web in the direction of travel, constraining successive increments of the advancing web into cylindrical surfaces, the axes about which said surfaces are traced extendingtransversely of the direction of travel of the web, moving the web so constrained through the web deforming zone, while progressively increasing to a predetermined figure and at a predetermined rate the di mension of each successive cylindrical web increment measured transverse to the direction of web travel and simultaneously decreasing to a predetermined figure and at a predetermined rate its dimension measured in the direction of web travel, and removing the web from the output end of the web deforming zone when'it has been cross stretched and longitudinally shrunk to the predetermined figure.

25. A cross stretching'apparatus comprising a carrier consisting of a plurality of spaced, parallel, extensible carrier elements, a cam positioned on each side of said carrier, said cams having duplicate cam slots, a plurality of cam followers in each of said cam slots, rotatable means for moving said carrier elements in a closed curved path defined by said cam slots, said cam slots being eccentric to the axis of rotation of said rotatable means, a portion of said closed path constituting a web deforming zone having a feed end and an output end, said cams diverging from each other from said feed end to said output end,'means for moving a nonwoven web into engagement with one of said carrier elements at said feed end, each of said carrier elements having its opposite ends secured to one of said cam followers, whereby said carrier elements are stretched in a direction transverse to the direction of Web travel as they are moved through said web deforming zone, means to hold said web in engagement with said carrier elements as said carrier elements are moved through said Web deforming zone, whereby said web is progressively cross stretched with said carrier elements as it is moved through said web deforming zone, means for shrinking said web longitudinally as it is moved through said web deforming zone, and means to remove said web from said carrier at the output end of said web deforming zone.

References Cited in the file of this patent UNITED STATES PATENTS GreatBritain Nov. 16, 1933 

